Vibrato is a technique of the left hand and arm in which the pitch of a note varies in a pulsating rhythm. While various parts of the hand or arm may be involved in the motion, the end result is a movement of the fingertip bringing about a slight change in vibrating string length. Violinists oscillate backwards, or lower in pitch from the actual note when using vibrato, since perception favors the highest pitch in a varying sound. Vibrato does little, if anything, to disguise an out-of-tune note: in other words, vibrato is a poor substitute for good intonation. Still, scales and other exercises meant to work on intonation are typically played without vibrato to make the work easier and more effective. Music students are taught that unless otherwise marked in music, vibrato is assumed or even mandatory.

Vibrato can be produced by a proper combination of finger, wrist and arm motions. One method, called "hand vibrato," involves rocking the hand back at the wrist to achieve oscillation, while another method, "arm vibrato," modulates the pitch by rocking at the elbow. A combination of these techniques allows a player to produce a large variety of tonal effects.